Hopper is a search engine for making trips. We use information extraction, machine learning, distributed computing and custom search algorithms to transform ridiculously huge volumes of data into useful information. Interested? Get in touch.
We hire smart people who get the job done. Yeah, we use a lot of Java. And RoR. And Hadoop, Cassandra, etc. We use AWS and we run a DC stuffed with custom-configured servers. In general, the knowledge of a specific technology/language/framework we already use can be helpful, but not a requirement. Chances are, you don't know everything you need to know to do this job. So willingness and ability to learn is a requirement.